1. Field of the Invention
The present invention relates to an optical memory, especially to an optical memory which can be read from and written to.
2. Background Information
Conventionally, an optical disk is a device for recording information as an optical signal. A magneto-optical disk is presently thought to be the best way to make an optical disk which can be read from and written onto. An industry standard relating to it has now been prepared. (Nikkei Electronics, 91-2-4, p. 75)
The reading and writing of information on an optical disk is done sequentially because the information is put in sequence on a magnetic head. The access time for such disk is twenty or thirty milliseconds, which is approximately a thousand times more than the access time for an IC memory. Because the access speed of an optical disk is extremely slow, such disks are generally inappropriate for performing random access of two-dimensional information.